The present invention relates generally to shaving apparatus, and specifically shaving apparatus that utilize a shearing technique to cut hair bristles between a rotary cutter and a fixed blade.
The current methods for removing hair from the human body, by shaving, as opposed to epilation, involve two basic approaches: the razor approach, wherein a very sharp blade is pushed against the skin at an angle, thereby cutting hair; and the screen approach, wherein a thin fenestrated metal screen is moved across the skin, exposing hair though the holes and cutting them by a mechanized, typically motorized, cutting element.
In the sharp razor blade approach, the energy for cutting is provided by the hand driving the razor across the skin of the user, typically by the hand of the user him/herself. The conditions of cutting hair are a compromise between the ease of cutting a soft (or softened) hair (or hair bristle) and having the necessary counter-force against the blade's force which can only come from the hardness of the hair bristle. Apart from being a compromise difficult to optimize daily on a variety of hair bristles, the sharpness of the blade and its angle pose a constant risk of nicks and cuts, as the blade is driven forcefully across the skin.
In the screen approach of most motorized shaving apparatus, the problem of safety is mitigated since the skin and the cutting elements are separated by the screen. Moreover, the hair bristles which penetrate the screen through its holes are given a prop to be cut against; hence, the lack of a counter-force for cutting is also mitigated to some extent. However, in order to arrive at an efficient cutting condition, the hair bristle must enter a hole and be perpendicular to the skin, requirements which are not always met unless the screen is constantly moved across the skin. Still, when the hair bristle is eventually cut at the optimal angle, it cannot be cut close to the skin due to the separating screen.
One cutting technique which requires minimal force for cutting hair can be effectuated with scissors. Scissors cut hair at the crossing point of two blades which do not have to be very sharp in order to cut the hair due to the fact that the blades contact the hair from substantially opposite directions in the plane of cutting, mutually providing each other with a counter-force for cutting. It is impractical to use scissors for daily shaving.